1. Technical Field
The invention relates generally to the manufacture of ophthalmic lenses such as contact, corneal implant, and intraocular lenses, and other small plastic or glass objects of similar shape, and more particularly to a method of making such lenses or objects with a high degree of precision at low cost by using an excimer laser.
2. Background Information
Ophthalmic lenses are normally manufactured by a mechanical process in which a block of polymehthylmethacrylate (PMMA) is machined while being adhesively held on a support. The machining is quite difficult because of the small size of the lens and the intricacy of the shape into which the lens must be machined.
Typically, three operations must be performed to shape a lens. For one, the workpiece must be cut out from a blank to form, for example, an integral optic and haptic. In addition, the surface of the workpiece must be machined to the desired optical specifications, which may include convexities or concavities of varying radii at different points on the surface of the lens, and the edges of the workpiece must be radiused or rounded.
In the prior art, the edge rounding step alone typically required 7-14 days of gemstone tumbling, and precision was hard to accomplish in all of the steps.